My invention relates to vehicle door operating apparatus. More particularly, the invention pertains to apparatus to close and open a vehicle door through a spindle drive and rod arrangement and using a lift motion to seal and lock the closed door.
It is known to use a pneumatically powered rotary actuator connected by rods and levers to rotate a door spindle to open and close vehicle doors, particularly the two-part doors on transit buses. However, most known arrangements do not provide effective door sealing when in the closed position. Looseness of the doors and the associated equipment tends to develop after a short term of use of the vehicle. This results in considerable rattling noise and loss of heated or cooled air during corresponding seasons. There is thus a need for door control apparatus which will provide positive door movement in both opening and closing actions, a better sealing and locking or latching of the closed door, and yet allow release of the locked door if pneumatic power, e.g., air pressure, to actuate the door controller is lost. This feature is necessary to permit a manual opening of the door in the absence of pressurized air, especially during emergency conditions.
Accordingly, an object of my invention is an improved door operating apparatus which provides positive movement of the doors, in both closing and opening directions, and a secure sealing and locking of the closed doors.
Another object of the invention is a pneumatic door actuator to open and close a vehicle door with a positive sealing and locking in the closed door position.
A further object of the invention is a door operating apparatus in which a rack and pinion movement is driven by a pneumatically actuated piston to develop reversible rotary motion which is transmitted to open and close the doors, and to open a valve at the end of a closing stroke of the piston to power a lifting cylinder to lock and seal a closed door.
Yet another object of my invention is door operating apparatus including a rack and pinion arrangement actuated by pressurized air to provide a rotary motion to drive the door to its closed and open positions, further including an integral pneumatic cylinder which provides a lifting force to move a closed door into a locked and sealed condition, so that loss of air pressure releases the door from the locked condition for manual movement during emergency operations.
A still further object of my invention is a rack and pinion assembly, powered by a pneumatically operated piston, which converts linear piston motion into a rotary motion and is coupled to move a vehicle door between its open and closed positions, and an associated lift rod, powered by another piston operated by pneumatic pressure provided through a valve actuated by the rack piston at its full closing stroke, which lifts a closed door to a locked and sealed position held during vehicle movements.
Other objects, features, and advantages of my invention will become apparent from the following specification and appended claims when taken in connection with the accompanying drawings.